JP2005136391A - Circuit substrate, design support equipment and method for the same, design support program, and design support program recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board which makes probing by the third party difficult and raises tamper resistance, while solving problems related to the current technology and manufacturing cost. <P>SOLUTION: A signal line 21 carrying confidential signals that require tamper resistance and components 32, 33 connecting with the signal line 21 through a terminal are arranged in the component built-in layer 13 of a circuit substrate 10. From an observation point 34 arranged on the surface of the circuit substrate 10, only confidential signals enciphered through a pre-determined component 31 are output. The observation and control of confidential signals from the outside can be performed by decoding encryption worked out at the component 31 about signals appearing at the observation point 34. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a portable terminal, a circuit board, a design support apparatus and method for a circuit board, a design support program, and a design support program recording medium, and more specifically, a circuit board having tamper resistance, and the circuit board The present invention relates to an apparatus and method for supporting design, a program for executing the method, a computer-readable recording medium recording the program, and a portable terminal incorporating the circuit board.

  In recent years, with the development of digital information technology and the explosive spread of digital information communication infrastructure, it has become common to process content such as music, images, videos and games as digital information. The contents converted into digital information can easily be illegally obtained by eavesdropping, eavesdropping, impersonation, etc., or illegally copied or illegally tampered with a recording medium storing content data. For this reason, it is a big problem to establish a security system that protects the rights of the copyright holder of the content and the profits of the distributor, and a technology for protecting the digitalized work is required. In the following description, the difficulty of unauthorized access to confidential information such as content and signals is referred to as tamper resistance.

  Various security techniques with improved tamper resistance using communication media have been known. In many cases, discrimination of a legitimate system and data encryption are realized by an encryption / authentication technique or the like. As a typical example, when accessing the confidential data storage area where confidential data that requires protection of copyrighted work is stored, exchange of random numbers and response values between devices is performed to authenticate each other. In addition, there is a challenge response type mutual authentication technology that permits access only when it is legitimate. Also, for secret data communication, cryptographic communication using random numbers or response values for mutual authentication is performed to prevent unauthorized decryption.

  On the other hand, in order to improve tamper resistance in a circuit board on which components and the like are mounted and wired, one of the conditions is the difficulty of probing a signal line for transmitting digital information. This is because information converted into digital signals can be easily reproduced with the same quality as long as the signal can be probed to determine its logic. The more difficult it is to read a signal on the circuit board, that is, the probing, the more difficult it is to analyze and copy digital information by unauthorized access from the outside. The easier the probing, the easier the signal extraction. Digital information can be easily analyzed and copied.

Various security techniques for this circuit board have been known. For example, there is a technique in which a circuit portion that processes confidential information is made into a one-chip IC so that a signal of the confidential information does not flow on the circuit board. Moreover, the circuit part which processes confidential information is included by resin etc. In addition, there is a technique in which components are arranged so as to cover a probable portion on a signal line through which a signal of confidential information flows (see Patent Document 1).
JP 2002-299842 A JP 2000-242673 A

  However, the method of making the circuit portion for processing the confidential information into a single chip IC or including it with a resin or the like cannot use an off-the-shelf IC or care for all the chips and wiring on the circuit board. It is unrealistic considering the current technology and manufacturing cost. In addition, not only a third party but also a developer or a designer (hereinafter, referred to as a designer or the like) cannot confirm a confidential signal after making a one-chip IC or including a resin. In addition, when a conventional encryption / authentication technology in communication is applied to a circuit board, it is necessary to incorporate logic for realizing the technology into all LSIs that handle digital information. It is unrealistic considering the aspect. In addition, as disclosed in Patent Document 1, the method of covering the signal line of the confidential information with a component has a problem that it can be easily probed if the component is removed. Thus, with the conventional technology, it is very difficult to completely conceal the signal line on which the confidential information on the circuit board flows.

  Therefore, an object of the present invention is to provide a circuit board having improved tamper resistance by making probing difficult by a third party while solving problems in the current technology and manufacturing cost. In addition, an object of the present invention is to provide a circuit board design support apparatus and method, a design support program, and a design support program recording medium.

  The present invention is directed to a circuit board having a multilayer structure in which components can be embedded in an inner layer between boards. And in order to achieve the said objective, the circuit board of this invention has wired the signal line through which the said confidential signal flows so that a predetermined confidential signal may not appear on the surface of a circuit board observably. This circuit board is suitable for use in portable terminals such as mobile phones and PDAs.

  Here, in order to enable a specific user such as a designer to arbitrarily extract a confidential signal while ensuring tamper resistance, a signal line through which the confidential signal flows and a predetermined observation point provided on the surface of the circuit board It is preferable that a part for external access for connecting is built in the inner layer so that a specific user can observe and control a secret signal through the part for external access.

  Typically, the external access component is provided with an encryption function, and the secret signal is subjected to predetermined encryption and output to the observation point. In this case, the specific user observes and controls the secret signal by decrypting the encryption applied to the signal appearing at the observation point. When there are a plurality of concealment signals, different encryption may be performed for each concealment signal classified according to a predetermined classification method. As this encryption function, a scramble engine is conceivable. When there are a plurality of secret signals, a plurality of scramble engines corresponding to the number of classifications may be used.

  Alternatively, the external access component may be provided with a high-speed interface function capable of high-speed sampling of the secret signal, and the secret signal may be compressed and output to the observation point. In addition, the external access component may be provided with an output selection function so that the output / non-output of the secret signal to the observation point can be selected when the circuit board is shipped. In addition, the external access component may be a component that transmits a signal such as a zero ohm resistor or a bus buffer so that the output / non-output of the secret signal to the observation point can be selected by mounting / non-mounting on the circuit board. Good. Alternatively, the external access component may be provided with a debugging function for debugging a component mounted on the circuit board so that mounting / non-mounting can be selected at the time of shipment of the circuit board. In this case, the debug signal for observing and controlling the operation of the component may be subjected to predetermined encryption and output to the observation point.

  On the other hand, in order to ensure tamper resistance without considering the extraction of the confidential signal by a specific user, either or both of the components that input or output the confidential signal should be incorporated in the inner layer. Is preferred. When the component that inputs or outputs the secret signal is in a shape that the connection terminal is hidden while mounted on the circuit board, it can be arranged on the surface of the circuit board by connection via a signal line through which the secret signal flows. To.

  The present invention is also directed to a design support apparatus that supports the design of a circuit board having a multilayer structure in which components can be incorporated in an internal layer between boards. And in order to achieve the said objective, the design assistance apparatus of this invention is equipped with the basic composition which consists of a detection part, an arrangement | positioning part, and a wiring part, and the additional structure which consists of a check part.

  The detection unit detects the secret signal based on predetermined information necessary for designing the circuit board. The arrangement unit designs a circuit by arranging components of a predetermined shape on the inner layer among components that input or output the confidential signal detected by the detection unit. The wiring unit designs a circuit by wiring a signal line through which a secret signal detected by the detection unit flows to an inner layer. The check unit checks whether or not the circuit designed in the placement unit and the wiring unit is designed so that the confidential signal does not appear observably on the surface of the circuit board. Output a warning. Here, the part having a predetermined shape is preferably a part having a shape in which the connection terminal is hidden at least when mounted on the circuit board.

  Each process performed by the detection unit, the placement unit, the wiring unit, and the check unit of the design support apparatus described above can be regarded as a design support method that provides a series of processing procedures. That is, in the design support device, a secret signal is detected based on predetermined information necessary for designing the circuit board, and a component having a predetermined shape is input to the inner layer among components that input or output the detected secret signal. Design the circuit by arranging and wiring the signal line through which the detected confidential signal flows to the inner layer, and design the circuit so that the confidential signal can be observed on the surface of the circuit board It is a design support method that checks whether or not it is designed so as not to appear, and outputs a predetermined warning when it is determined that it is not designed.

  Preferably, the design support method is provided in the form of a program for causing the design support apparatus to execute a series of processing procedures. This program may be recorded on a computer-readable recording medium.

  According to the above-described present invention, the circuit board is configured such that the signal line through which the confidential signal requiring tamper resistance flows, the component related to the input / output of the confidential signal, and the external access component are all formed in the inner layer, The structure is such that an encrypted secret signal is output. As a result, it is possible to improve tamper resistance by making it difficult for a third party to perform probing while ensuring observability and controllability by a designer or the like. In addition, perfect tamper resistance can be achieved by not mounting external access components at the time of product shipment. Furthermore, since encryption using the circuit board of the present invention is different from encryption in a conventional integrated circuit, any commercially available part and encryption part can be combined, and tamper resistance is provided at low cost. It is possible to develop a circuit board.

  Further, according to the present invention described above, the signal terminal is exposed to the surface when the circuit board is placed among the signal line through which the confidential signal requiring tamper resistance flows and the components related to the input / output of the confidential signal. All parts are configured in the inner layer, and the secret signal is not exposed on the surface. This makes it difficult to perform probing by a third party and improves tamper resistance. Furthermore, these circuit boards with improved tamper resistance can be easily designed with the above design support apparatus and method. Even if the design is not successful, a warning is notified to the designer and the like, so that a circuit design error can be prevented.

  The circuit board with improved tamper resistance according to the present invention is produced by using a multilayer board technology capable of incorporating components in an inner layer between the boards. Hereinafter, a characteristic circuit board structure according to the present invention will be described with reference to the drawings.

(First embodiment)
The circuit board according to the first embodiment of the present invention has signal lines for signals that require tamper resistance, such as confidential information, arranged on the inner layer, and allows the designers to observe and control confidential signals as necessary. This is a circuit board having the structure as described above.

  FIG. 1 shows a cross-sectional view of a circuit board 10 using a substrate structure according to a first embodiment of the present invention. As shown in FIG. 1, the circuit board 10 includes an upper board 11, an upper multilayer board 12, a component built-in layer 13, a lower multilayer board 14, and a lower board 15. Components 31, 32, and 33 are embedded in the component built-in layer 13. In FIG. 1, it is assumed that a signal line 21 that interconnects components 31, 32, and 33 is a signal line through which a signal that requires tamper resistance flows. A signal that requires tamper resistance refers to a signal that a circuit board designer, such as a microcomputer memory bus or a debugging signal line, does not want a third party to observe or control. Hereinafter, this signal is referred to as a secret signal. The signal line 21 does not appear as a foil or a via on the surface (the upper substrate 11 and the lower substrate 15) of the circuit board 10, and is wired only by the component built-in layer 13. The signal line 21 is connected to an observation point 34 exposed on the upper substrate 11 of the circuit board 10 via the component 31 and the via 22. The observation point 34 is a part for external connection such as a test pad, a test pin, or a connector.

  The component 31 in the circuit board 10 according to the first embodiment is a component that controls the connection between the signal line 21 and the observation point 34, in other words, an external access component. Various tamper resistances can be realized by providing the component 31 with various functions as described below.

1. Encryption Function If a component 31 having an encryption function such as a scramble engine is used, the secret signal flowing through the signal line 21 can be subjected to a predetermined encryption (scramble) and output to the observation point 34. For this reason, even if the observation point 34 is probed, the secret content is not known unless the encryption applied to the observed signal is decrypted. Therefore, only a designer who knows the encryption method can freely observe or control the confidential signal, so that tamper resistance against a third party is improved. The decryption of the code may be performed by connecting the decoding component 35 to the observation point 34 or the like. For example, the decode component 35 may be mounted at a predetermined position on the circuit board 10 (FIG. 2), or the decode component 35 mounted on another substrate may be externally connected using the cable 23 or the like ( FIG. 3).

  When there are a plurality of confidential signals, the same encryption may be applied to all the confidential signals using one encryption function, or two or more encryption functions may be used in advance. Different encryption may be performed for each classified confidential signal. In this way, by using a plurality of encryptions, it is possible to make probing by a third party more difficult and to improve tamper resistance.

2. High-speed I / F function When there are a plurality of confidential signals, it is conceivable that the observation points 34 are required as many as the confidential signals. In this case, a component 31 is used that operates at a cycle shorter than the cycle of the secret signal flowing through the signal line 21 and has a high-speed interface (I / F) function for parallel-serial conversion of an input signal. As a result, the secret signal flowing through the signal line 21 can be sampled and compressed at high speed in accordance with the period, and the compressed signal can be output. Therefore, the number of observation points 34 exposed to the outside can be reduced. Therefore, the area occupied by the observation point with respect to the area of the circuit board is reduced, and the manufacturing cost of the circuit board can be reduced.

3. Output selection function If it is only necessary to observe or control the secret signal before product shipment, a component 31 having an output selection function may be used. The component 31 is typically a switch that can be connected / disconnected, but may be a jumper component such as a zero ohm resistor or a component that transmits a signal such as a bus buffer. In the case of the former component 31, it is switched to the connection side only when it is necessary for the observation and control of the secret signal, and is finally shipped in the state switched to the non-connection side. In the case of the latter component 31, it is arranged and connected only when it is necessary for observation and control of the secret signal, and is finally shipped in an unmounted state on the circuit board 10. By doing so, the signal line 21 is concealed in the inner layer of the circuit board 10, and perfect tamper resistance can be realized for a third party. Note that components having an encryption function and a high-speed I / F function may not be mounted at the time of product shipment.

4). Debug Function If it is only necessary to observe or control the secret signal before shipping the product, a component 31 having a debug function may be used. With the debug function, for example, the signal line 21 is monitored, and when a trigger such as an address or data specified in advance by a designer or the like is generated, the state before and after the occurrence is saved in the memory in the component 31 and later This is a function that allows designers to observe the contents of memory. Alternatively, when the signal line 21 is monitored and a trigger such as an address or data designated in advance by a designer or the like is generated, the operation of necessary parts such as the parts 32 and 33 is stopped, and the designer or the like is later This is a function for resuming (and re-stopping) the operation according to the instruction. Development may be performed by mounting the component 31 having the debugging function, and finally, the circuit board 10 may be shipped in an unmounted state. By doing so, the signal line 21 is concealed in the inner layer of the circuit board 10, and perfect tamper resistance can be realized for a third party.

  Note that the component 31 may be provided with both an encryption function and a debugging function. If such a component 31 is used, there is an effect that a designer or the like can develop without worrying about signal delay due to encryption.

  Further, in addition to the encryption function, the component 31 may be provided with a microcomputer function for controlling a part of the circuit board 10 and a microcomputer debug function (for example, JTAG (Joint Test Action Group)). (FIG. 4). If such a component 31 is used, it becomes possible to encrypt the debug information of the microcomputer and output it to the observation point 34, which has the effect of improving tamper resistance. In this case, the encryption function unit, the microcomputer function, and the microcomputer debug function unit may be different parts (FIG. 5).

  As described above, the circuit board according to the first exemplary embodiment of the present invention includes all the signal lines through which the confidential signal that requires tamper resistance flows, the components related to the input / output of the confidential signal, and the external access components in the inner layer. It is configured to output a secret signal that is encrypted on the surface. As a result, it is possible to improve tamper resistance by making it difficult for a third party to perform probing while ensuring observability and controllability by a designer or the like. In addition, perfect tamper resistance can be achieved by not mounting external access components at the time of product shipment. Furthermore, since encryption using the circuit board of the present invention is different from encryption in a conventional integrated circuit, any commercially available part and encryption part can be combined, and tamper resistance is provided at low cost. It is possible to develop a circuit board.

  The circuit board 10 shown in FIG. 1 is an example, and the internal layers of the circuit board include all the inner layers in addition to the upper multilayer board 12, the component built-in layer 13, and the lower multilayer board 14. The configuration of the circuit board can be freely determined as long as components can be embedded, such as a component built-in layer, or a combination of a multilayer substrate and a component built-in layer alternately.

(Second Embodiment)
In the circuit board according to the second embodiment of the present invention, the signal line of the secret signal is wired in the inner layer, and the components such as the two-terminal component and the QFP (quad flat package) component are exposed. A circuit board having a structure arranged in layers.

  FIG. 6 shows a cross-sectional view of a circuit board 40 using the board structure according to the second embodiment of the present invention. As shown in FIG. 6, the circuit board 40 includes an upper board 41, an upper multilayer board 42, a component built-in layer 43, a lower multilayer board 44, and a lower board 45. On the upper substrate 41, a component 61 is placed. In the component built-in layer 43, components 62 and 63 are built. In FIG. 6, it is assumed that the signal line 51 that connects the component 62 and the component 63 is a signal line through which a confidential signal that requires tamper resistance flows. The signal line 51 is connected to the component 61 via the via 52.

  The component 61 placed on the upper substrate 41 in the circuit board 40 according to the second embodiment is a component whose signal terminals are not exposed to the surface when placed, that is, cannot be probed. For example, a BGA (Ball Grid Array) package or the like. All of the components such as the components 62 and 63 whose signal terminals are exposed on the surface when placed are arranged in the component inner layer 43. With this configuration, if the component 61 is not removed from the circuit board 40, the secret signal flowing through the signal line 51 that requires tamper resistance does not appear outside.

  As described above, the circuit board according to the second embodiment of the present invention has a signal line when a confidential signal that requires tamper resistance flows and a signal terminal that is placed among components related to the input / output of the confidential signal. All the parts exposed on the surface are formed in the inner layer, and the secret signal is not exposed on the surface. This makes it difficult to perform probing by a third party and improves tamper resistance.

(Third embodiment)
In the third embodiment, an example in which the substrate structure described in the first and second embodiments is used for a mobile terminal such as a mobile phone or a PDA will be described.
As is well known, personal information about a user and a call partner, a password, and the like are stored in the mobile phone. Since these personal information and passwords are also confidential information that is not desired to be known by a third party, it is desirable that they have tamper resistance against fraudulent acts. Therefore, as a circuit board of a cellular phone, a memory component in which confidential information is stored and a signal line through which a signal related to the confidential information flows may be used in the inner layer. 7A and 7B are diagrams showing a specific example of this configuration. The nonvolatile memory 73 (Flash memory) in which the confidential information is stored, the working memory (SRAM) 74 used for processing the confidential information, A signal line 81 through which a signal related to confidential information flows and a damping resistor 72 are configured in the component built-in layer 43, and the CPU 71 is configured on the upper substrate 41. Needless to say, which components and signal lines should be configured in the component built-in layer 43 are different depending on the processing circuit of the mobile phone and the signals handled as confidential information.

  In recent years, a system for paying money using a non-contact communication function mounted on a mobile phone, an IC card or the like has been put into practical use. For example, the ICOCA (registered trademark) system implemented by JR West. In this system, payment or charging of money is performed only by data communication. Therefore, tamper resistance is particularly important in a mobile phone or the like equipped with the system so as not to suffer financial damage. Therefore, in a mobile phone or the like equipped with such a system, a memory component that stores confidential information, a signal line through which a signal related to the confidential information flows, and a component that performs non-contact communication processing (or a processing program are stored) The circuit board having the (memory) 75 and its signal line 83 all formed in the inner layer may be used. FIG. 7C is a diagram showing a specific example of this configuration.

  As described above, by adopting the same board structure for circuit boards used in portable terminals such as mobile phones and PDAs, it is possible to make probing by a third party difficult and improve tamper resistance. 7A to 7C exemplify the case where the substrate structure of the second embodiment is applied to a mobile terminal, but the first and the like that can ensure observability and controllability by a designer or the like. The substrate structure of the embodiment may be applied.

  Note that, as in the circuit boards of the first to third embodiments described above, a signal line through which a confidential signal that requires tamper resistance and components related to input / output of the confidential signal are all configured in an internal layer. If this is the case, probing in the same state is impossible. However, it is also conceivable that a malicious third party peels or scrapes the surface of the circuit board to expose the components of the built-in layer, signal lines, and the like. Therefore, as a countermeasure against such circuit board peeling or excavation by a third party, the circuit board is preferably provided with a component destruction function. This component destruction function can be provided in the circuit board as follows, for example.

The adhesive strength between the component built-in layer and the component related to the input / output of the secret signal is set to be larger than the breaking strength of the component itself. Thereby, when it is going to peel off a component from a component built-in layer, components themselves can be destroyed.
Alternatively, the adhesive strength between the component built-in layer and the component related to the input / output of the secret signal is set to be larger than the connection strength between the component and the signal line (wiring pattern) through which the secret signal flows. Thereby, when it is going to peel a component from a component built-in layer, the electrical connection between a component and a signal wire can be interrupted.
Alternatively, the component built-in layer has a residual stress larger than the breaking strength of the component related to the input / output of the secret signal or the connection strength between the component and the signal line through which the secret signal flows. Here, the residual stress is a stress remaining in the component built-in layer, for example, a force when returning from a bent state. This residual stress is maintained when the component built-in layer is intact, and is released when any damage is applied to the component built-in layer. Thereby, when the component built-in layer is cut or polished, the component itself can be destroyed or the electrical connection between the component and the signal line can be interrupted.

(Fourth embodiment)
In the fourth embodiment, a device (such as a CAD device) that supports the design of the circuit board described in the first to third embodiments will be described. A feature of the circuit board design support apparatus and method according to the fourth embodiment is that a well-known circuit board design apparatus and method are allowed to consider a secret signal. A known circuit board designing apparatus and method are described in detail in, for example, Patent Document 2.

  FIG. 8 is a functional block diagram conceptually illustrating a circuit board design support apparatus according to the fourth embodiment of the present invention. 8, the design support apparatus includes a command input unit 801, a data input unit 802, an input command analysis unit 803, a design information storage unit 804, a display unit 805, a tamper resistance signal detection unit 806, A tamper resistant arrangement portion 807, a tamper resistant wiring portion 808, and a tamper resistant signal check portion 809 are provided.

  The command input unit 801 is an input interface such as a keyboard and a mouse, and receives input of various design commands by a user operation. The data input unit 802 inputs circuit diagram information or the like created by a circuit diagram creation CAD device or the like (not shown). The input command analysis unit 803 analyzes the design command input to the command input unit 801 and determines the command type. This design command includes a component placement command and a wiring command. The design information storage unit 804 is design information necessary for designing a circuit board, such as circuit diagram information, board information, layer configuration information, component information, connection information, signal information, and design reference information input from the data input unit 802. Remember. Information regarding whether or not the signal is a confidential signal is included in the signal information, for example, by being specified by a designer or the like. The display unit 805 displays a display screen corresponding to the design process of the circuit board to be designed.

  As a method for specifying a secret signal, a designer or the like may instruct signal names such as TCKTDI, TMS, TDO, NRD, and NWT one by one. Alternatively, a predetermined spelling such as * CS * or ADR * may be designated and a signal including the specified spelling may be used as a secret signal. Alternatively, the signals included in the circuit board may be grouped, and one of the groups may have a tamper-resistant attribute, thereby providing a secret signal.

With further reference to FIG. 9, a circuit board design support method related to tamper resistance will be described.
The tamper resistant signal detection unit 806 detects a secret signal from the signal information stored in the design information storage unit 804 (step S901). The tamper resistant arrangement unit 807 includes, as an inner layer, a component having a predetermined package (a component from which a terminal is exposed) among components connected to the confidential signal detected by the tamper resistant signal detection unit 806. A design process is performed in which the other components are arranged in an area where the other components can be arranged (step S902). The component placement method in this design process may be a method used in a conventional CAD apparatus, or a designer or the like may instruct from the command input unit 801. Even if the signal terminal is exposed, for example, if it is a BGA package, a CSP package, or the like, it may be arranged on the upper or lower surface of the circuit board according to the judgment of the designer or the like.

  The tamper-resistant wiring unit 808 performs a design process in which after the components are arranged by the tamper-resistant arranging unit 807, the secret signal is wired only in the area of the inner layer and the other wiring is wired in the area where wiring is possible. (Step S903). The tamper resistant signal check unit 809 is a signal line on which the confidential signal is wired only in the inner layer of the circuit board designed by the tamper resistant placement unit 807 and the tamper resistant wiring unit 808, or the confidential signal flows. It is checked whether or not the component terminals are exposed on the surface of the circuit board (step S904). When a component terminal, a signal line, a via, or the like through which a confidential signal flows is exposed on the surface of the circuit board, a warning is notified to the designer or the like (steps S905 and S906). As a warning notification means, a message may be displayed on the screen of the display unit 805, a warning part may be highlighted, or a beep sound or the like may be notified. A log may be left. The designer who received the warning performs component placement and signal wiring again (repeats step S902 and subsequent steps).

  As described above, by using the circuit board design support apparatus and method according to the fourth embodiment of the present invention, the circuit board with improved tamper resistance described in the first to third embodiments can be easily obtained. It becomes possible to design. Even if the design is not successful, a warning is notified to the designer and the like, so that a circuit design error can be prevented.

  The circuit board, the circuit board design support apparatus and method of the present invention makes it difficult to probe a secret signal that requires tamper resistance flowing through the circuit board, and enables the designer and the like to observe and control it. This is useful for improving tampering properties.

Sectional drawing of the circuit board 10 using the board | substrate structure which concerns on the 1st Embodiment of this invention. Sectional view of the circuit board 10 with the decoding component 35 connected to the observation point 34 Another sectional view of the circuit board 10 in which the decoding component 35 is connected to the observation point 34 The figure which shows an example of the components incorporated in the component incorporation layer 13 The other figure which shows an example of the component incorporated in the component incorporation layer 13 Sectional drawing of the circuit board 40 using the board | substrate structure which concerns on the 2nd Embodiment of this invention. Sectional drawing of the circuit board 70 which concerns on the 3rd Embodiment of this invention. The figure which shows an example of the component incorporated in the component incorporation layer 43 The figure which shows another example of the component incorporated in the component incorporation layer 43. Functional block diagram conceptually illustrating a circuit board design support apparatus according to a fourth embodiment of the present invention. The flowchart which shows the process sequence of the design support method of the circuit board based on the 4th Embodiment of this invention.

Explanation of symbols

10, 40, 70 Circuit board 11, 41 Upper board 12, 42 Upper multilayer board 13, 43 Component built-in layer 14, 44 Lower multilayer board 15, 45 Lower board 21, 51, 81, 83 Signal lines 22, 52, 82 Via 23 Cable 31 to 33, 35, 61 to 63, 71 to 75 Parts 34 Observation point 801 Command input unit 802 Data input unit 803 Input command analysis unit 804 Design information storage unit 805 Display unit 806 Tamper resistance signal detection unit 807 Tamper resistant placement portion 808 Tamper resistant wiring portion 809 Tamper resistant signal check portion

Claims (21)

A circuit board having a multilayer structure in which components can be embedded in an inner layer between boards,
A circuit board in which a signal line through which the secret signal flows is wired so that a predetermined secret signal does not appear observably on the surface of the circuit board. A component for external access that connects a signal line through which the confidential signal flows and a predetermined observation point provided on the surface of the circuit board is incorporated in the inner layer,
The circuit board according to claim 1, wherein a specific user can observe and control the secret signal through the external access component. The external access component has an encryption function, performs a predetermined encryption on the secret signal, and outputs to the observation point,
The circuit board according to claim 2, wherein the specific user can observe and control the secret signal by decrypting a cipher applied to the signal appearing at the observation point.   4. The circuit board according to claim 3, wherein when there are a plurality of secret signals, encryption is performed differently for each secret signal classified according to a predetermined classification method. 5.   The circuit board according to claim 3, wherein the encryption function is a scramble engine.   The circuit board according to claim 4, wherein the encryption function is a plurality of scramble engines according to the number of classifications.   The circuit according to claim 2, wherein the external access component has a high-speed interface function capable of high-speed sampling of the secret signal, and compresses the secret signal and outputs the compressed signal to the observation point. substrate.   3. The circuit according to claim 2, wherein the external access component has an output selection function, and output / non-output of the secret signal to the observation point can be selected when the circuit board is shipped. substrate.   The external access component is a component for transmitting a signal such as a zero ohm resistor or a bus buffer, and the output / non-output of the secret signal to the observation point is selected by mounting / non-mounting on the circuit board. The circuit board according to claim 8, wherein:   3. The circuit according to claim 2, wherein the external access component has a debugging function for debugging a component mounted on the circuit board, and can be selected to be mounted / not mounted at the time of shipment of the circuit board. substrate.   The external access component further includes a debug function for debugging the component mounted on the circuit board, and performs a predetermined encryption on a debug signal for observing and controlling the operation of the component and outputs the debug signal to the observation point. The circuit board according to claim 3, wherein:   The circuit board according to claim 1, wherein either or both of components for inputting or outputting the concealment signal are incorporated in the inner layer.   When the component that inputs or outputs the secret signal has a shape in which the connection terminal is hidden while mounted on the circuit board, it can be placed on the surface of the circuit board by connection via a signal line through which the secret signal flows. The circuit board according to claim 1, wherein the circuit board is provided. A portable mobile device,
A circuit board on which components for executing communication processing are mounted using a multilayer structure in which components can be embedded in an internal layer between the substrates;
An interface connected to the circuit board,
The circuit board is characterized in that a predetermined secret signal does not appear on the surface of the circuit board in an observable manner, components arranged to handle the secret signal, and wiring of signal lines through which the secret signal flows are made. Terminal. It further includes a non-contact communication processing unit that transmits and receives information by non-contact communication,
15. The portable terminal according to claim 14, wherein the arrangement of components for handling a secret signal transmitted and received by non-contact communication and the wiring of a signal line through which the secret signal flows are configured in an inner layer of the circuit board. . A design support device for supporting the design of a circuit board having a multilayer structure in which components can be embedded in an internal layer between boards,
Based on predetermined information necessary for the design of the circuit board, a detection unit for detecting a confidential signal,
Among the components that input or output the secret signal detected by the detection unit, an arrangement unit that designs a circuit by arranging components of a predetermined shape in the inner layer;
A design support apparatus comprising: a wiring unit that designs a circuit by wiring a signal line through which the confidential signal detected by the detection unit flows to the inner layer.   The circuit designed in the placement unit and the wiring unit checks whether the concealment signal is designed so that it cannot be observed on the surface of the circuit board. If not, a predetermined warning is given. The design support apparatus according to claim 16, further comprising a check unit that outputs.   The design support apparatus according to claim 16, wherein the part having the predetermined shape is a part having a shape in which a connection terminal is hidden when mounted on at least a circuit board. A design support method for supporting the design of a circuit board having a multilayer structure in which components can be embedded in an internal layer between boards,
Detecting a concealment signal based on predetermined information required for circuit board design; and
Among the components that input or output the secret signal detected in the detecting step, a step of designing a circuit by arranging a component of a predetermined shape in the inner layer;
Wiring a signal line through which the confidential signal detected in the detecting step flows to the inner layer, and designing a circuit;
Checking whether the circuit designed in the placing step and the wiring step is designed so that the secret signal does not appear observably on the surface of the circuit board;
And a step of outputting a predetermined warning when it is determined that the design is not performed in the checking step. A program executed by a design support device that supports the design of a circuit board having a multilayer structure in which components can be embedded in an internal layer between boards,
In the design support device,
Detecting a concealment signal based on predetermined information required for circuit board design; and
Among the components that input or output the secret signal detected in the detecting step, a step of designing a circuit by arranging a component of a predetermined shape in the inner layer;
Wiring a signal line through which the confidential signal detected in the detecting step flows to the inner layer, and designing a circuit;
Checking whether the circuit designed in the placing step and the wiring step is designed so that the secret signal does not appear observably on the surface of the circuit board;
A program for executing a step of outputting a predetermined warning when it is determined that the design is not performed in the step of checking. A computer-readable recording medium recorded with a program executed by a design support apparatus that supports design of a circuit board having a multilayer structure in which components can be embedded in an internal layer between boards,
In the design support device,
Detecting a concealment signal based on predetermined information required for circuit board design; and
Among the components that input or output the secret signal detected in the detecting step, a step of designing a circuit by arranging a component of a predetermined shape in the inner layer;
Wiring a signal line through which the confidential signal detected in the detecting step flows to the inner layer, and designing a circuit;
Checking whether the circuit designed in the placing step and the wiring step is designed so that the secret signal does not appear observably on the surface of the circuit board;
A recording medium for recording a program for executing a step of outputting a predetermined warning when it is determined that the design is not performed in the checking step.

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